CONCORD, N.C. -- Four-time Sprint Cup champion Jeff Gordon said his career could be shortened if back problems that have grown progressively worse don't improve.

Gordon had a facet block injection earlier this week to ease the pain that has made being in the car increasingly uncomfortable. The points leader said he had an MRI last month that revealed arthritis and other ailments he would not identify.

"If my back were the way it was at Bristol this year, it definitely would shorten my career," Gordon said on Thursday at Lowe's Motor Speedway. "I can't race like that forever, for long periods of time."

Gordon, 37, ranks sixth on NASCAR's all-time wins list with 82 victories. He hopes the block helps him get to the bottom of his back problems and finish his career on his own terms.

"Every driver throughout history has fought some kind of battle to stay in the car and stay competitive," Gordon said.

David Newton covers NASCAR for ESPN.com. He can be reached at dnewtonespn@aol.com.